In Spirogyra, the thallus is silky, hair like, unbranched and filamentous. The cells comprising the filament are cylindrical in form with transverse end walls. They are longer than their breadth. The cell contains a ceil wall surrounding the protoplast. The cell wall consists of concentric layers. The inner wall consists of cellulose and outer of pectose. The pectose layer is responsible for slimy or slippery touch of filament. The protoplast is differentiated into plasma membrane, cytoplasm, nucleus one or more chloroplasts with pyrenoids and a large central vacuole.